1. Field of the Invention
The present invention relates to a method for rehabilitating existing pipes such as clean water and sewage pipes, agricultural water pipes, power pipes, communication pipes and the like, and to a rehabilitation pipe segment or a box culvert rehabilitating segment used in the method.
2. Description of the Related Art
There are pipe-lining methods for lining the internal circumferential surface of a pipe to repair the pipe without digging the pipe from the ground in the case that clean water and sewer pipes or other pipes buried underground have aged. These methods employ a pipe-lining material comprised of a flexible tubular resin-absorbing material that is impregnated with a curable resin and covered with a highly airtight film on the exterior thereof.
The pipe-lining material is everted and inserted into the pipe by hydrostatic pressure. The pipe-lining material is heated while being pressed against the internal circumferential surface of the pipe to be repaired, and the curable resin impregnated in the pipe-lining material is cured to thereby line the internal circumferential surface of the pipe (Japanese Laid-open Patent Application 2003-165158).
In order to rehabilitate an existing pipe having a large diameter, Japanese Laid-open Patent Application Nos. 2003-214098 and 2005-299711 disclose a pipeline rehabilitation method using segments that are sequentially coupled in the circumferential direction and the lengthwise direction of an existing pipe and assembled as a rehabilitation pipe. The gap between the external surface of the rehabilitation pipe and the inner wall surface of the existing pipe is filled with a grout material or another filling material that is cured to construct a composite pipe.
Segments used to assemble the rehabilitation pipe are formed as integrally molded plastic panel blocks partitioned by an inner surface plate, two side plates, and two end plates. Ribs and reinforcement plates are suitably provided to increase the strength of the segment.
With conventional pipe rehabilitation or box culvert rehabilitation in which a lining material impregnated with a thermosetting resin is used, the lining material must be made thick and a large amount of resin is required when an attempt is made to provide the rehabilitation pipe with strength. Therefore, a large amount of ice, cooling water, or another cooling medium is required to prevent the resin from setting during transport of the lining material. As a result, there is a problem in that costs are increased and construction work is difficult.
When assembled as a rehabilitation pipe or rehabilitation structure, a rehabilitation pipe or a box culvert and other laid conduits has its external circumferential surface exposed to the existing pipe. Even when a grout material or another filling material is filled between the existing pipe and the rehabilitation pipe or the rehabilitation structure, there is a problem in that the filling material is directly impacted from the exterior in the case that the existing pipe or the like is damaged, or damage to the rehabilitation pipe or the like is increased because the strength of the filling material is low. With a rehabilitation pipe in which segments are used, there is little internal skeletal structure in the circumferential direction, and deformation readily occurs under external force, water hammering, or other internal pressure. Furthermore, a segment formed in the shape of an integrally molded plastic block as described in the prior art must be modified in plate thickness in order to increase the strength of the segment, and costs are considerably increased when a mold is fabricated for resin molding.
In either case, a conventional rehabilitation pipe may be suitable for repairing an existing pipe, but the strength of such a rehabilitation pipe is insufficient as a self-supporting pipe because there are cases in which the pipe is damaged or broken when the pipe receives a large impact from the exterior or the interior thereof.
An object of the present invention is to solve such problems and to provide a method for rehabilitating an existing pipe using a lining material and segments so as to strengthen the existing pipe and construct a self-supporting pipe, and to provide a segment used in the method for rehabilitating an existing pipe or a box culvert.